It's the most basic of all questions, but someone asks it at least once a week.  In this article, I will explain what channel means in music and mixing

 I use the word "channel" to describe where you record each element of your mix.  When you record your vocals, kick, snare, guitar, etc. you record each one on a "channel."  The number of channels you have decides the price you pay for a mixing/mastering job. 

The Example Below Would Be Considered A 10 Channel Mix/Master

You have a lead vocal, background vocal, bass, kick, snare, cymbals, acoustic guitar, organ, synth, and lead guitar.  10 channels in total and you would be charged the 10 channel price listed on the website.  Also, remember, mastering is free with all mixing jobs.

Back to my online mastering prices page.